Conventionally, a fuel cell system is known which uses a fuel cell such as a solid oxide fuel cell (SOFC) or a molten carbonate fuel cell (MCFC). A solid oxide fuel cell operates in a high temperature range of about 600° C. to 1000° C. and a molten carbonate fuel cell operates in a high temperature range of about 500° C. to 900° C.
Conventionally, when the supply of raw fuel gas to a fuel cell system is stopped due to natural disasters such as an earthquake, a power failure, a striking of a bolt of lightning, or a typhoon, the fuel cell system undergoes emergency shutdown (for example, see Patent Literature 1).
A fuel cell system is also known in which a raw fuel line is provided with an adsorber adsorbing raw fuel gas and the supply of raw fuel gas is stopped using a supply shutdown valve disposed in the raw fuel line and a discharging pump is activated to discharge the raw fuel gas from the adsorber to the fuel cell at the time of emergency shutdown (for example, see Patent Literature 2).